Effects of ionizing radiation on expression of genes encoding cytoskeletal elements: kinetics and dose effects.
We examined the modulation in expression of genes encoding three cytoskeletal elements (beta-actin, gamma-actin, and alpha-tubulin) in Syrian hamster embryo (SHE) cells following exposure to ionizing radiations. Early-passage SHE cells were irradiated in plateau phase with various low doses (12-200 cGy) of neutrons, gamma-rays, or x-rays. RNA samples were prepared from cells at different times postexposure and were analyzed for levels of specific transcripts by northern blots. The results revealed that alpha-tubulin was induced by both high-linear energy of transfer (LET) (neutrons) and low-LET (gamma-rays and x-rays) radiations with similar kinetics. The peak in alpha-tubulin mRNA accumulation occurred between 1 and 3 h postexposure; for gamma-actin mRNA, accumulation was similarly induced. For both gamma-actin and alpha-tubulin, the higher the dose during the first hour postexposure (up to 200 cGy gamma-rays), the greater the level of mRNA induction. In contrast, mRNA specific for beta-actin showed decreased accumulation during the first hour following radiation exposure, and remained low up to 3 h postexposure. These results document the differential modulation of genes specific for cytoskeletal elements following radiation exposure. In addition, they demonstrate a decrease in the ratio of beta-actin:gamma-actin mRNA within the first 3 h following gamma-ray exposure. These changes in mRNA accumulation are similar to those reported in some transformed cell lines and in cells treated with tumor promoters, which suggests a role for changes in actin- and tubulin-mRNA expression in radiation-mediated transformation.
Woloschak
G E
GE
Biological and Medical Research Division, Argonne National Laboratory, Illinois 60439.
Shearin-Jones
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P
Chang-Liu
C M
CM
D000199:Actins / Q000235:genetics*; D000818:Animals; D002478:Cells, Cultured; D006224:Cricetinae; D003599:Cytoskeleton / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D015870:Gene Expression / Q000528:radiation effects*; D066298:In Vitro Techniques; D008647:Mesocricetus; D009502:Neutrons; D012333:RNA, Messenger / Q000235:genetics; D011839:Radiation, Ionizing; D013997:Time Factors; D014404:Tubulin / Q000235:genetics*; D014965:X-Rays
D000199:Actins; D012333:RNA, Messenger; D014404:Tubulin